class Car():
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0
        self.gas_tank = 300
    def fill_gas_tank(self):
        print("This car need " + str(self.gas_tank) + "L gas.")
    def get_descriptive_name(self):
        long_name = str(self.year) + ' ' + self.make + ' ' + self.model
        return long_name.title()
    def read_odometer(self):
        print("This car has " + str(self.odometer_reading) + " miles on it.")
    def update_odometer(self, mileage):
        if mileage >= self.odometer_reading:
            self.odometer_reading = mileage
        else:
            print("You can`t roll back an odometer!")
    def increment_odometer(self, miles):
        self.odometer_reading += miles

class Battery():
    def __init__(self, battery_size = 70):
        self.battery_size = battery_size
    def descibe_battery(self):
        print("This car has a " + str(self.battery_size) + "-kWh battery.")
    def get_range(self):
        if self.battery_size == 70:
            range = 240
        elif self.battery_size == 85:
            range = 270
        message = "This car can go approximately " + str(range)
        message += " miles on a full charge."
        print(message)

class ElectricCar(Car):
    def __init__(self, make, model, year):
        super().__init__(make, model, year) # 这里注意super的使用，继承父类不需要写self
        self.battery = Battery()

    def fill_gas_tank(self):
        print("This car doesn`t need a gas tank!") # 这里对父类方法进行了重写

my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_name())
my_tesla.battery.descibe_battery()
my_tesla.fill_gas_tank()
my_tesla.battery.get_range()